船厂二级生化出水的回用技术应用研究

通过小试模拟船厂二级生化出水的中置式混凝沉淀工艺运行过程,研究了PAC和PAM投加量对出水水质的影响。结果表明,PAC和PAM最佳投量分别为40和0.3 mg/L。根据小试结果进行中试投药,结果显示NaClO的最佳投量为10 mg/L、PAC和PAM最佳投量与小试一致;中试对COD的去除率要高于小试,且出水水质达到《城市污水再生利用城市杂用水水质》(GB/T18920—2002)与《城市污水再生利用景观环境用水水质》(GB/T 18921—2002)水质标准;除总氮外,中试出水其余指标均达到《地表水环境质量标准》(GB 3838—2002)的Ⅳ类水质要求,且部分指标达到Ⅰ类和Ⅲ类水质要求。回用水处理总价为0.65元/t,厂区自来水费为2.38元/t,中水回用装置流量按30 t/h来计,则企业每年可节约自来水量为26.3×104t,每年将节省45.5万元;同时还可以减排污水量为26.3×104t,削减COD量为10.52 t、NH3-N量为0.39 t、TP量为0.26 t。

Application Study of Reclaimed Water Reuse Technology for Secondary Biochemical Effluent of Shipyard

In the small-scale test simulating the operation of intermediate flocculation and sedimentation tank of secondary biochemical effluent of shipyard,the effect of PAC and PAM dosages on the effluent quality was investigated.The results show that the optimal dosages of PAC and PAM are 40 mg/L and 0.3 mg/L respectively.The pilot-scale test results based on the small-scale test show that the optimal dosage of NaClO is 10 mg/L,and the optimal dosages of PAC and PAM are the same to those in the small-scale test.The removal rate of COD in the pilot-scale test is superior to that in the small-scale test,and the effluent quality meets the requirements of the Reuse of Urban Recycling Water—Water Quality Standard for Urban Miscellaneous Water Consumption(GB/T 18920-2002) and the Reuse of Urban Recycling Water―Water Quality Standard for Scenic Environment Use(GB/T 18921-2002).Except for total nitrogen,other indexes meet the Ⅳ criterion specified in the Environmental Quality Standards for Surface Water(GB 3838-2002),and some indexes meet the Ⅰand Ⅲ criteria.The total treatment cost of reclaimed water is 0.65 yuan/t while the enterprise tap water cost is 2.38 yuan/t.If the flow of reuse device is 30 t/h,the enterprise can save tap water of 26.3×104 t which is equal to 455 000 yuan and reduce the wastewater discharge of 26.3×104 t,COD of 10.52 t,NH3-N of 0.39 t and TP of 0.26 t every year.